This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Increased hair cortisol concentrations have been correlated with stress exposure in both human and non-human primates, and hair cortisol is now gaining attention as a biomarker for stress-related health problems. However, to date, no studies have examined its usefulness for predicting future mental health problems. This study determined whether hair cortisol was a significant predictor of later anxiety in young rhesus macaques (Macaca mulatta).